It is known to provide lighting for vehicles. For example, it is known to provide incandescent lighting systems for use in the interior of a motor vehicle. One disadvantage of such incandescent lighting systems is that there is a tendency for such systems to provide inefficient power conversion to visible light. For example, current incandescent lamps in such lighting systems only produce about 4 lumens per watt. In addition, the cost of the electrical support system for use with such incandescent lighting systems tends to be relatively high due to the large current draw which each incandescent lamp requires in order to produce adequate light output. For example, it is presently estimated that due to the required increase in alternator output and increase in wire size to accommodate existing incandescent lamps, the cost per watt is about $0.42. Present incandescent lamps use about 12 watts per lamp. Another problem with existing incandescent lamps of the type provided for use with a motor vehicle is that such lamps include a filament which tends to fail when subjected to the extreme vibration and mechanical shock prevalent in motor vehicle applications.
One disadvantage when considering the fabrication and maintenance of incandescent lighting systems presently used inside motor vehicles, is that such systems tend to include multiple components that are not interchangeable and are not necessarily optimized to each other. Each such system includes several parts which are usually custom manufactured for each application.
Efforts to replace incandescent lighting systems for vehicle interior apparatus with filamentless, discharge lighting systems have also incurred problems. Presently, filamentless, discharge lighting systems require a lamp, a ballast and interconnecting wiring. Although such systems tend to be efficient and robust in a vibrating environment such as is incurred in motor vehicle applications, such systems require up to 1500 volts to start and several hundred volts for continued operation. Extreme care is required when installing such a system in order to prevent dangerous exposure to such high voltage to the automotive technician and the end consumer. For saftey, the electronic ballast may include additional circuits to sense an open circuit, or an excessive current draw, and shut down the system down or otherwise respond to protect the system, the automotive technician and the end consumer. In addition, the lamp and the ballast must be tuned to each other in each application for optimum performance and minimization of EMI. Typically, the lamp is sold separately and a system integrator is required to attach the lamp to the electronic ballast package for satisfactory operation. Another problem is that in some applications the filamentless discharge lamps in each vehicle are mounted at a remote location relative to the electronic ballast package the result of which is to increase the potential for electric shock hazard and electromagnetic interference.